1. Field of the Invention
This invention relates to a system for preventing crosswise meandering of an endless belt extended over a group of rolls in a single facet which produces a single-faced corrugated board by nipping a corrugating medium and a liner between a lower fluted roll and the endless belt extended over a plurality of rolls so as to paste them together.
2. Description of the Related Art
In a system for forming a single-faced corrugated board (so-called single facer), an upper fluted roll and a lower fluted roll each having wavy flutes formed on the circumference are rotatably supported between frames in a vertical relationship in such a way that they may engage with each other by their flutes, and a press roll is designed to be brought into press contact with the lower fluted roll via a corrugating medium and a liner which are the webs of the single-faced corrugated board. Namely, the corrugating medium, which is fed between the upper fluted roll and the lower fluted roll, is allowed to have a predetermined corrugation (flutes) when it passes between these rolls. A starchy glue is applied to the crests of corrugation thus formed by a gluing roll provided in a gluing mechanism. Meanwhile, the liner being fed from the side opposite to the corrugating medium via the press roll is pressed against the glued crests of the corrugating medium between the press roll and the lower fluted roll to be pasted together and form a single-faced corrugated board. The press roll employed in the conventional single facer is of a large-diameter metallic roll which is normally urged toward the lower fluted roll so as to apply a predetermined nip pressure to the corrugating medium and liner passing between these rolls. Since flutes consisting of continuous alternative repetition of crests and troughs are formed at a predetermined pitch on the circumference of the lower fluted roll, the rotation center of the lower fluted roll and that of the press roll shift slightly as the point of press contact therebetween shifts from the trough to the crest or vice versa. Thus, as the result that the rotation centers of these rolls make cyclic reciprocating motions to be closer to or farther from each other as they rotate, great vibration and big noise are generated during formation of the single-faced corrugated board, causing the working environment in the plant to be worsened considerably. Besides, since both the press roll and the lower fluted roll are made of rigid metallic materials, an impact is periodically applied to the press roll (so-called the hammer phenomenon) every time the crests of the lower fluted roll are abutted against the press roll. Accordingly, linear press marks corresponding to the pitch of the crests of the lower fluted roll are formed horizontally on the surface of the liner in the thus formed single-faced corrugated board, disadvantageously.
As a countermeasure for the problems described above, it is proposed to use an endless belt in place of the metallic press roll so as to nip the corrugating medium and the liner in cooperation with the lower fluted roll. More specifically, the endless belt, which is extended over a plurality of rolls to run freely, is disposed adjacent to the lower fluted roll, and the corrugating medium and the liner passing between the lower fluted roll and the endless belt are adapted to be nipped therebetween and pasted together by bringing the endless belt closer to the outer surface of the lower fluted roll. Thus, the use of the endless belt can prevent generation of great vibration and big noise and also formation of press marks on the single-faced corrugated board.
In the single facer employing an endless belt described above, the endless belt and the lower fluted roll must be abutted against each other parallelwise over the full length (in the axial direction of the roll), so that it is impossible to form crowns on the rolls over which the belt is extended. However, it is extremely difficult to form an endless belt having a uniform thickness and a uniform inner peripheral size over the full width thereof, and most of such belts involve minor errors. Accordingly, such endless belt extended over the group of uncrowned rolls tends to undergo crosswise biasing or meandering due to the errors inherent in itself to be displaced from the bonding zone where the corrugating medium and the liner are pasted together, causing defective pasting therebetween.
Under such circumstances, it is proposed to prevent meandering of the endless belt extended over the group of rolls by shifting the axes of these rolls to slightly cross each other. However, since the direction of meandering, the meandering stroke, etc. due to the errors and the like inherent in the endless belts vary one by one, the biasing direction and the biasing amount of these rolls must be adjusted every time the belt is replaced. Namely, each roll must be provided with an adjusting mechanism, making the structure of the single facet complicated and also leading to cost elevation, disadvantageously. It can also be pointed out that the spaces for disposing the respective adjusting mechanisms must be secured, and thus the size of the single facer is enlarged. Besides, adjusting operations are required every time the endless belt is replaced to increase the loss time, causing reduction of production efficiency. Incidentally, meandering of belt can happen during running due to changes in the operational conditions, abrasion of the belt, etc., even if adjustment of rolls is duly performed before starting the single facet.
In such cases, the operation of the single facer must be stopped to make readjustment, causing again reduction in the production efficiency.
This invention is proposed in view of the problems inherent in the prior art described above and in order to solve them successfully, and it is an objective of the invention to provide a system for preventing meandering of an endless belt in a single facet, which has a simple structure and can securely prevent meandering of the endless belt.